During 2017 we started to use a new type of speed lights – Hahnell Modus 600RT. Previously we have been using Godox V860II for more than two years, and they have been working great and without any problems except when using under cold conditions.
It seems like their batteries were not up to the job when the temperature went below minus 5C. Here in Finland we have a long cold winter, and with several trips to lapland every year it was becoming a problem. The Godox AD360 and 180 models using the PB960 batteries are working excellent in cold weather, if you wrap them in plastic to prevent moisture to access cable connections between battery and flash.
Using a flash system with external batteries is not that smart, and often speed light are more easy to transport, setup and in this case have a very effective battery.
A few years back we swapped out the Nikon batteries with Hahnel batteries, and that improved battery life by about 35% in cold conditions, so we already knew that their batteries were excellent for jobs in winter conditions. The Hahnel Modus speed light are using a battery design similar to the ones they produce to other divices like DSLR cameras, so it was a logical step to take.
Mixing different flash systems and triggers are not smart – its really not smart, and it will always create problems during a workday, so in this case the Hahnel modus flashes has become tools for extreme usage.
So far this winter they have not misfired or had any other problems so we cross our fingers for the first wedding shoot at the end of the month.